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1. Field of the Invention
The present invention relates to real-time distribution of digitally encoded messages over a data network, such as the Internet. More specifically, the present invention relates to a system and method for controlling transmission of digitally encoded messages using any desired communication protocol, including the native protocol of the communicating devices.
2. Background of the Invention
FIG. 1 is a schematic diagram of a prior art system 101 for real-time transmission of digitally encoded messages (DEMs). Where MCDs 102 and 106 are fax machines, for example, the DEMs are fax messages. MCD 102 sends a DEM to MCD 106. MCD 102 sends telephony data representative of a DEM to a public-switched telephone network (PSTN) 104 over line 108 using the T.30 protocol. Likewise, the PSTN transmits the telephony data to MCD 106 over line 110 using the T.30 protocol.
The PSTN 104 of system 101 has two attributes that facilitate transmission of DEMs. First, the PSTN 104 provides a guaranteed bandwidth. Once a connection is made, MCD 102 and MCD 106 communicate using the full bandwidth allocated to the telephony connection provided by the PSTN 104. Second, there is a guaranteed latency between the time that MCD 102 sends the telephony data and the time MCD 106 receives the telephony data.
The PSTN-based transmission of DEMs suffers from several disadvantages. First, long distance charges must often be incurred in completing the DEM transmission from MCD 102 to MCD 106. Second, the bandwidth of the telephony connection is limited relative to other forms of communication such as communication over data networks. Third, even with full bandwidth of the telephony connection available, many data transfer protocols (for example, fax) can be conducted using less than one tenthxe2x80x94and are designed to use no more than one halfxe2x80x94of the full bandwidth available.
To avoid the disadvantages associated with system 101, DEMs have been transmitted over data communication networks, for example, the Internet. FIG. 2 illustrates a schematic of a prior art system 241 for transmitting DEMs over a data network. In system 241, MCD 242 transmits telephony data representative of a DEM to a server 244 over line 250 using the T.30 protocol. Server 244 is assumed to be equipped with a data conversion card (not shown) to convert the telephony data to computer data. Server 244 transmits the computer data to a server 246 over line 252 using the TCP/IP protocol. Line 252 represents a computer network, for example the Internet. The server 246 converts the computer data to telephony data using a card (not shown). The telephony data is transmitted to MCD 248 over line 254 using the T.30 protocol.
There are two disadvantages associated with system 241. First, there is no guaranteed bandwidth. Although a computer network is capable of providing greater bandwidth than a telephony-based system, there is no guarantee that any bandwidth will be available when it is needed, unless, possibly, the network is dedicated to the transmission of DEMs. Second, there is no guaranteed minimum latency. Thus, there is no guarantee that a DEM sent by MCD 242 will reach MCD 248 within any minimum delay. This is problematic with many DEM transmissions because the MCD 242 and MCD 248 generally must maintain synchronization with one another. For example, where MCDs 242 and 248 are fax machines, they must resynchronize with one another at the end of each transmitted page. For fax machines, this resynchronization must occur within 5 to 7 seconds. If the required resynchronization does not occur within the required time frame, MCDs 242 and 248 will assume that the connection has been lost and they will hang up. Unfortunately, latency over a data network such as the Internet can be on the order of 30 seconds or more. Thus, the prior art system 241 will likely cause disrupted DEM delivery due to lost connections resulting from loss of synchronization because no minimum latency can be guaranteed.
xe2x80x9cDEM,xe2x80x9d as used herein, shall mean digitally encoded message.
xe2x80x9cMCD,xe2x80x9d as used herein, shall mean message communicating device. A facsimile machine is one example of an MCD.
xe2x80x9cPSTN,xe2x80x9d as used herein, shall mean public-switched telephone network.
xe2x80x9cDCN,xe2x80x9d as used herein, shall mean data communications network, including, but not limited to, wide area networks, intracompany networks, intercompany networks and other internodal networks such as the Internet.
The present invention solves the problems associated with conventional systems by providing a control process to handle the protocol among nodes transferring DEMs over a data communications network. The control processes on the various nodes communicate with one another to determine any particular node""s availability for message communication. If a connection is made for message communication, the control processes on the communicating nodes control message transfer according to a particular protocol, and transfer the DEMs over the DCN in real time. The protocol can be any data communications protocol, including the data communications protocol native to the communicating devices.
The control process in the preferred embodiment includes a parent process and a child process. The parent process is responsible for managing communication between nodes, i.e., the parent process is responsible for managing the DCN aspects of a DEM communication. DEM communication is also referred to herein as a DEM transaction. Thus, the parent process isolates the child process from DCN related functions. The child process controls the hardware aspects of a DEM communication. This control includes managing telephony hardware and performing any telephony related functions. The child process, therefore isolates the parent process from the hardware aspects of DEM communication. Preferably, the child process communicates with a particular MCD using its native protocol. The parent and child work together according to a protocol to ensure that DEM communications are established within the latency time required to maintain synchronization.
When DEMs cannot be transmitted over the data communications network, the control process attempts to route DEMs over a secondary path. The secondary path is also a data network. Thus, the bandwidth and cost advantages associated with transmitting DEMs using data networks rather than telephony lines are preserved. In addition, the secondary path provides an auxiliary route for DEMs when they cannot be immediately transmitted over the primary DCN.
The secondary path of the preferred embodiment includes two store-and-forward servers. The first store-and-forward server is operatively coupled to a DEM server on the sending side of the data network. The second store-and-forward server is operatively coupled to a DEM server on the receiving side, and also to the first store-and-forward server. In operation, when the primary path is unavailable, the sending-side DEM server transmits DEMs from the sender MCD to the first store-and-forward processor, where they are stored. Subsequently, the first store-and-forward processor delivers the DEM to the second store-and-forward processor. The second store-and-forward processor then sends the DEM to the receiver-side DEM server where it will be delivered to a receiver MCD.
The secondary path for DEM transmission allows the present invention to complete DEM transmission in real-time when the primary path is unavailable for DEM transmission.
Thus, one objective of the present invention is to provide a minimum guaranteed latency between the time that a digitally encoded message is sent over a DCN and the time that it is received.
Another object of the present invention is to provide real-time transmission of digitally encoded messages.
Yet another object of the present invention is to provide cost-efficient digitally encoded message transmission in real-time using least-cost routing techniques.
Another object of the present invention is to provide communications over a DCN using any desired protocol, including the native protocol of the communicating devices.
Another objective of the present invention is to provide a backup communications option, such that it the real-time attempt fails for any reason, the sender has the option to allow a store-and-forward attempt to deliver a message along a secondary path
These and other objects of the present invention are described in greater detail in the detailed description of the invention, the appended drawings and the attached claims.